Compositions of matter



United States Patent :z,sz2,z6s

COMPOSITIONS or MATTER Hugh B. Hix, Wilmington, DeL, .assignor to E. I. duPont deNemours and-Company; Wilmington, Del.,"a corpo- "ratio'njof Delaware Nd-Drawing. Applicatiornarugustt 1,1956 Serial No. 601,341

TZiilitims. (C1, 75- 174) This 'invefition relates fto "niobium-base alloys, and more particularly "to "niobium base "alloys containing titanium and. at least one'o'ther' element of thegronpcom (prising aluminumfberyllium, carbon, cobalt,-*iron, man- 'ganese,"'mo1y.bdenum, nickeL: silicon, tantalum, tungsten, "vanadium-and zirconium. v

Superior,"workable' alloys which possess strength and oxidation resistance 'athigh temperature are used "as materials "Ioffcons'truction in 'all types of-technical and industrial e uipment. The' development efmor adva need nuclear reactors and gas turbines is dependent u ion thefava'ilabil'ity OfiSllCh' alloys. Furthermore, there is a need 'for betterj high temperature alloys in theconstruction of di'es for high temperature working ofm'etals and the-construction ofchemical reactors, oil refining e'quir'a'me'ntflnd"the like. A combination-of workability, high temperature strength, and high temperature corrosionre sistance in an alloy has -'proved difii'c'ult to achieve,- and considerable time and efiforthave been dev'oted to the search for such metals.

Ithas nowbeenfound 'that workable alloys possessin unusually high corrosionresistance'and strength at temperatures above ll00" C.can 'be produced by alloying titanium a'tid' 'niobium"and'specifid' added elements 'inthe aniounts seftorth herein. 7

u i-s, th'e'retore,'=an object of this invention to provide ear the I production of =ni6bium base --'all'oys which are paft iciilarly =re'sistai1t to h-igh temperatu're oxidation. Ar'tother object of m'y invention is to provide' niobium- -base alloys which are responsive to heat-treatment. Aribtlier bject ofi my' -iiiveiitibn is to prdduee nieuiumb'ase alldys -"to wuieh a film or -metal oXide will fiimly adhere when the alloy is heated to relativel hi gh tempei'a'tur'es arid-cooled. Other ob'jeCts arid advantages of theupresent invention will be 1 apparent in VieW of the following-detailed descriptions thereof.

The v alloys of this t invention comprise eoiiipositio'ns t eoritaining about "-1--30% by weight of titaiiium, -about 01T6%iby'we'ight' :of alununum, about 0+5% by-"Weight of beryllium, about 0-2% by weight of ca'rbOnJabout "by*weight-of cobalt,'-about -=0 10% by' weight of iron, .zabout ii-40% by "weight of manganese, 'about fa rtim -2thout l 14 -byweight," the balance being essenriallyuniobium. g

il-rt a mo're preferred embodiment' thealloy T'of-thisinfollow conventional 'me'tal "meltingand reme'lting' 'te'ch- 'ice 2 eniques usingwinertgcoriditions. Measured amounts of a the individual-metal constituents are melted together, solidified and remelted 'until homogeneity is :obtained. The final melt .thenallowe-d.tocoolandsolidify into a 5 .klesired shape. aThe ease materialzthus obtainedtis ,of. a -workablemetal rwi-thstrengthand oxidation. resistance at high temperatures,-and it is suitablerasia material oficonstruction in high temperature equipment. Any of a number of types of meltingequipmnt may be used to prepare wthese newlalloys. lnutherspecificaexamples which'iappear daternini this i specification, an :arc melting s furnactzvotvthe type describedtbyawsKrolluin "iT'ransa'cfions. @flthEtElEC- trochemic-al 'Sd'cietyft'veil. r7 8,:'1p.-.,"35'-47, 1940,- was;11seid. This furnace has an integral, water-cooled copper crucible in which the charge mayBeLrnIted and solidified. The @harge iaiif nlletal constituents for' 'thiwf-i-1rna'ee' maybe in an eofivenient renn, e *g povvde shoh wiregsponge, ete. A consumable arc"electrdde furnaee as describdf in U. S. Patent 2640860 is another' apparatus which would prove suitable. Also, one could use a cotnbination of non-consumable and consumable electrodes in a double melt furnace such has ..is described .in U. S. :Patent 12,541,764. A-eentinuous "fee'di't rnace such as listle- "'scfibedlinU..,S.;P..B..Report 111,083 would :also prepare 'TtheallQYs. Eurther'mormlmel ting.could be accomplished by inductively heating the charge"in.a suitablecru cible. Regardless of the melting apparatus used, care should be exercised to protect the' ir'io'lten metals from the normal atmosphere since-tcontaminatiomofi.theualloyabywoxygen, wnitrogen, ;etc., is -to-,be avoided. To -provide proteetion .againsta'contamination, themeltirggashohldrbe:aearriedqo t underqinertcondition s,-: such: asa-ane atmosphere efmrgon or a protective slag or a combination ;of:-,a'iprotect-ive slag and a controlled atmosphere. The practice of using an inert atmosphere sudh as'argonf'helium, etc., when melting v me tals, iscwell known'iinttheiart.

:Thevfo'llbwingiexamplesiaretgpresentedt to illustrate the upreparation of rspecific valleys of uthisuinveiitionuandtthe -outstanding cpropet tiesmf =t-heseitall'oysr These' eitatnples are illustrative only andnarelnotato be consttued as litniting the invention. --All, percentsvset forth in the ensuing examples refer to percents by weight.

.TExamplcII g -Aruniform melticontainingl 23 titanium, m ma-rel, 3 aluminum and 7 nib-him;waepreparednuy meuin the elemental metals--together and then alternately solidifying and remelting the alloy composition six times. The "melting apparatus was an ard meltiijg furnace having .an zintegral, Mater-cooled eepp'er cru'eible, t as described {by eZKrou -in the fTraasactions of the lElect-roche'mieal '80- emery" publication reterrew to abeve. 1 Apoit'ion ,fiffthe melt was poured into a water-cooled copper mold having a cylindrical cavity 4' intdiameter and 2" deep. During 5 the above-described operations an atmosphere of. helium Was maintained ahtive "the inetals'ito 'jmev'eint contamination. une:castingireenveredrrern me maid was" forged and -maehinedtntq -anozzle for sprayingdnolten salts; s'uch as MgCl inchemical rocesses. I 6 The alloy compositionpoftthis example Was tested for high temperature oxidation ,resistance by thegfollowing procedure: i

A weighedsampleof the-alloy (in aj'po'reelainerucible -Which'is slottedf'to" insn readequate access lfiair to 'the ingot) is p'laeed-inafG1obartfumace andreigposedltor at least 16 hours atl-OOO C. totinbiif'piirge em cu. tt/min. After exposure, the isample is cooled and weighed,,and the amount-.ofpxidatiomis determined as the percent 'weightggaid in" the, sa ple,

Under thesecoriditions' "the alloy showdsawei ghtpgain of Unallo'yednidbiumfshows,a weight,gain .'of26% "under theh'airiie conditions.

Example 11 maintained and the alloy composition was alternately remelted and solidified six times, whereupon a homogeneous ingot was obtained. The weight gain according to the test described in Example I was 2.5%.

Example Ill Using'the procedure of Example II, an alloy of the following composition was prepared: 20% titanium, 10% aluminum and 70% niobium. The weight gain according to the test described in Example I was 1.7%.

Example IV Using the procedure of Example H, an alloy of the following'composition was prepared: 80% niobium, 17% titanium, 1% tungsten, 0.5% beryllium, 1.5% tantalum. The weight gain according to the test described in Example I was 2.0%.

Example V Using the procedure of Example H, an alloy of the following composition was prepared: 55% niobium, 29% titanium, manganese, molybdenum, 1% aluminum. The weight gain according to the test described in Example I was 1.3%.

Example VI Using the procedure of Example II, an alloy of the following composition was prepared: 78% niobium, 13.5% titanium, 3% aluminum, 2.5% iron, 3% molybdenum. The weight gain according to the test described in Example I was 2.2%.

Example VII Using the procedure of Example II, an alloy of the following composition was prepared: 70% niobium, 16% titanium, 4% aluminum, 2% iron, 5% molybdenum, 3% beryllium. The weight gain according to the test described in Example I was 1.8%.

Example VIII Using the procedure of Example H, an alloy of the following composition was prepared: 80% niobium, titanium, 1% silicon, 4% aluminum. The weight gain according to the test described in Example I was 2.0%.

Example IX Using the procedure of Example II, an alloy of the following composition was prepared: 65% niobium, 15% titanium, 15 molybdenum, 5% aluminum. The weight gain according to the test described in Example I was 2.2%.

Example X Using the procedure of Example II, an alloy of the following composition was prepared: 90% niobium, 7% titanium, 3% aluminum. The weight gain according to the test described in Example I was 2.5%.

Example XI Example XII Using the procedure of Example II, an alloy of the following composition was prepared: 80% niobium, 5% titanium, 2.5% iron, 2.5% molybdenum, 10% aluminum. The weight gain according to the test described i E amplelwas 2.1%.

Example XIII Using the procedure of Example II, an alloy of the following composition was prepared: 70% niobium, 10% titanium, 8% vanadium, 6% molybdenum, 6% aluminum. The weight gain according to the test described in Example I was 1.5

Example XIV Using the procedure of Example II, an alloy of the following composition was prepared: 70% niobium, 15% titanium, 3.5% iron, 4.5% aluminum, 7% molybdenum. The weight gain according to the test described in Example I was 1.9.

Although it is preferable to use metals which are of a high purity, a fair amount of variance in purity can be tolerated before product quality suifers appreciably. The

alloys of the working examples are made from commercially available metals containing less than 1% incidental impurities. Commercial niobium nearly always contains tantalum (usually in amounts up to 5%) which is hard to detect and very difficult to separate. Therefore, the niobium used in the specific examples no doubt contained tantalum which is reported as niobium rather than as an incidental impurity. In addition to the tantalum which is present in commercial niobium, this invention contemplates the addition of tantalum to the alloy composition in amounts up to 20%. Those skilled in the art are readily aware of the presence of incidental impurities in commercial metals and of the presence of tantalum in commercial niobium, and these facts should be taken into consideration when practicing the invention and construing the claims.

The alloys of this invention have the advantages of strength at high temperatures, ease of. working, and resistance to corrosion. In addition to these advantageous properties, these alloys are superior base metals since they have resistance to oxidative deterioration at high temperatures. This property has been particularly deficient in niobium metal. These alloys are suitable for many diverse applications. Among these are the construction of pieces of equipment which must operate above 800 C.

Particular stress has been laid upon the use of these alloys in high temperature equipment, such as jet engine parts, nuclear reactor and gas turbine parts because of their outstanding properties. However, it should be emphasized that its use is not limited to high temperature conditions or to any piece of equipment described herein.

Since it is obvious that many changes and modifications can be made in the above-described details without departing from the nature and spirit of the invention, it is to be understood that the invention is not to be limited to said details except as set forth in the appended claims.

This case is a continuation in part of my copending application Serial No. 550,764, filed December 2, 1955.

I claim:

1. A niobium base alloy comprising about 1-30% b weight of titanium, about O10% by weight of aluminum, about 05% by weight of beryllium, about 02% by weight of carbon, about 0-5% by weight of cobalt, about 0-10% by weight of iron, about 010% by weight of manganese, about 0-20% by weight of molybdenum, about 05% by weight of nickel, about 0-2% by weight of silicon, about 0-20% by weight of tantalum, about 0-5% by weight of tungsten, about 0-10% by weight of vanadium, and about 020% by weight of zirconium, the'sum total of Al, Be, C, Co, Fe, Mn, Mo, Si, Ni, Ta, W, V and Zr ranging from about 1-20% by weight, the balance being essentially niobium.

2. A niobium base alloy comprising about 5-25% by weight of titanium, about 05% by weight of aluminum, about 0 5 by weight of nickel, about 0-5 by weight of iron, about 07% by weight of molybdenum, the sum total of Al, Ni, Fe and Mo'being about 4-20% by Weight, the balance being essentially niobium.

No references cited. 

1. A NIOBIUM BASE ALLOY COMPRISING ABOUT 1-30% BY WEIGHT OF TITANIUM, ABOUT 0-10% BY WEIGHT OF ALIMINUM, ABOUT 0-5% BY WEIGHT OF BERYLLIUM, ABOUT 0-2% BY WEIGHT OF CARBON, ABOUT 0-5% BY WEIGHT OF CABALT, ABOUT GANESE, ABOUT 0-20% BY WEIGHT OF MOLYBDENUM, ABOUT GANESE, ABOUT 0-20% BY WEIGHT OF MOLYBDENUM, ABOUT 0-5% BY WEIGHT OF NICKLE, ABOUT 0-2% BY WEIGHT OF SILICON, ABOUT 0-20% BY WEIGHT OF ZIRCONIUM, THE SUM TOTAL WEIGHT OF TUNGSTEN, ABOUT 0-10% BY WEIGHT OF VANADIUM, AND ABOUT 0-20% BY WEIGHT OF ZIRCONIUM, THE SUM TOTAL OF AL, BE, C, CO, FE, MN, MO, SI, NI, TA, W, V AND ZR RANGING FROM ABOUT 1-20% BY WEIGHT, THE BALANCE BEING ESSENTIALLY NIOBIUM. 